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9 Apr 2024: Amphibole (hornblende). Amphibole hand specimen. Amphibole hand specimen. Formula. (Na,K). 0-1. Ca. 2. (Mg,Fe. 2+. ,Fe. 3+. ,Al). 5. Si. 6-7.5. Al. 2-0.5. O. 22. (OH). 2. Structure. Chain silicate. Crystal System. Crystal system: monoclinic () (-).

9 Apr 2024: Zircon crystal structure (tetragonal), CrystalMaker. Zircon is a common accessory mineral of many igneous rocks. Pleochroic haloes are formed by damage to the crystal lattice of enclosing minerals by the radioactive decay of elements such as Th and

9 Apr 2024: The olivine has decomposed to magnetite and serpentine. Relict olivine grains display characteristic curving cracks andClinopyroxene (augite). - ... Some simple twinning. Accessory minerals. - Opaque, interstitial, probably magnetite. Rock History.

9 Apr 2024: Chlorite crystal structure, CrystalMaker. Formula. (Mg,Fe. 2+. ,Fe. 3+. ,Mn,Al). 12. [(Si,Al). 8. O. 20. ](OH). 16. Structure. Sheet silicate. Crystal System. Crystal system: monoclinic () (-). Physical Properties. Colour in hand specimen: green.

9 Apr 2024: Browse Items (264 total). Page. of 27. Sort by:. Formula NaCl Structure Non-silicate Crystal System Crystal system: cubic Physical Properties Colour in hand specimen: colourless or white when pure, more typically orange or red due to inclusions of

9 Apr 2024: Alteration. Zonation. Accessory minerals:. - Sphene. - Magnetite. - Apatite. Rock History.

9 Apr 2024: Some areof magnetite, clinopyroxene and other minerals. Extensive alteration along abundant cracks. ... Groundmass. - Fine-grained. Plagioclase feldspar needles, clinopyroxene, some olivine (mostly altered), and opaques, probably magnetite.

9 Apr 2024: Halite cubic crystal structure with large Cl. -. anions (green) and small Na. cations (yellow). This mineral is commonly known as rock salt. Formula. NaCl. Structure. Non-silicate. Crystal System. Crystal system: cubic. Physical Properties. Colour

9 Apr 2024: Garnet (euhedral) in hand specimen. Formula. (Mg,Fe,Ca). 3. Al. 2. Si. 3. O. 12. Structure. Orthosilicate. Crystal System. Crystal system: cubic. Physical Properties. Colour in hand specimen: typically red. Cleavage: none. Hardness: 6-7.5. Optical

9 Apr 2024: The olivine has decomposed to magnetite and serpentine. Relict olivine grains display characteristic curving cracks andClinopyroxene (augite). - ... Some simple twinning. Accessory minerals. - Opaque, interstitial, probably magnetite. Rock History.